1. Field of the Invention
This application relates to the field of gantry depalletizers, for example, of the kind adapted for removing complete layers of articles from pallets. These articles can include, for example, beverage containers, such as six-packs of beverages in cans, plastic bottles and glass bottles.
2. Description of Related Art
A grapple clamp is disclosed in U.S. Pat. No. 5,253,974 which has four clamp jaws hinged to a frame in a rectangular or square orientation so as to engage a group of objects, such as a layer of beverage containers, with equal force from four sides. One or more load stabilizer blocks are adapted for insertion into hollow or empty spaces within the interior of the layers. Blocks of different shapes and sizes must be stored and used selectively to stabilize each different size and shape of the hollow space.
A depalletizer is disclosed in U.S. Pat. No. 5,582,504, for grasping and removing rows of objects stacked upon a pallet. The depalletizer is equipped with feelers which probe the top layer on the pallet in order to find out which is the initial row present in the top layer. The probing cycle is carried out so that all the rows present in the top layer are detected, whereupon grasping of the initial row is triggered. The feelers also detect whether the top layer is oriented horizontally.
A stacker crane order picker is disclosed in U.S. Pat. No. 3,716,147, which removes a predetermined number of articles from a matrix of articles. The apparatus includes sensing means which is associated with an article pickup means and operates to sense the number of articles supported by the article pickup means.
A device for lifting at least one material stack is disclosed in U.S. Pat. No. 4,911,608, which includes sensors for detecting the distance between a gripper and the stack.
The present invention improves on the foregoing by providing an apparatus for automating depalletization. Therefore, it is an object of the present invention to provide an apparatus that can automatically stack and unstack storage pallets.
Another object of the invention is an apparatus for stacking and unstacking storage pallets that is easily adaptable for use with different load types.
Yet another object of the invention is an apparatus that can automatically load and unload pallets stacked in multiple tiers, where the pallet on each tier may contain a different load type.
Still another object of the invention is an apparatus for stacking and unstacking a pallet having an irregular or off center load thereon.